diff options
Diffstat (limited to 'gl/m4/strcasestr.m4')
| -rw-r--r-- | gl/m4/strcasestr.m4 | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/gl/m4/strcasestr.m4 b/gl/m4/strcasestr.m4 new file mode 100644 index 0000000..4c2275f --- /dev/null +++ b/gl/m4/strcasestr.m4 @@ -0,0 +1,154 @@ +# strcasestr.m4 serial 25 +dnl Copyright (C) 2005, 2007-2020 Free Software Foundation, Inc. +dnl This file is free software; the Free Software Foundation +dnl gives unlimited permission to copy and/or distribute it, +dnl with or without modifications, as long as this notice is preserved. + +dnl Check that strcasestr is present and works. +AC_DEFUN([gl_FUNC_STRCASESTR_SIMPLE], +[ + AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS]) + + dnl Persuade glibc <string.h> to declare strcasestr(). + AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS]) + + AC_REQUIRE([gl_FUNC_MEMCHR]) + AC_CHECK_FUNCS([strcasestr]) + if test $ac_cv_func_strcasestr = no; then + HAVE_STRCASESTR=0 + else + if test $HAVE_MEMCHR = 0 || test $REPLACE_MEMCHR = 1; then + REPLACE_STRCASESTR=1 + else + dnl Detect https://sourceware.org/bugzilla/show_bug.cgi?id=12092 + dnl and https://sourceware.org/bugzilla/show_bug.cgi?id=23637. + AC_CACHE_CHECK([whether strcasestr works], + [gl_cv_func_strcasestr_works_always], + [AC_RUN_IFELSE( + [AC_LANG_PROGRAM([[ +#include <string.h> /* for strcasestr */ +#ifdef __GNU_LIBRARY__ + #include <features.h> + #if __GLIBC__ == 2 && __GLIBC_MINOR__ == 28 + Unlucky user + #endif +#endif +#define P "_EF_BF_BD" +#define HAYSTACK "F_BD_CE_BD" P P P P "_C3_88_20" P P P "_C3_A7_20" P +#define NEEDLE P P P P P +]], + [[return !!strcasestr (HAYSTACK, NEEDLE); + ]])], + [gl_cv_func_strcasestr_works_always=yes], + [gl_cv_func_strcasestr_works_always=no], + [dnl glibc 2.12 and cygwin 1.7.7 have a known bug. uClibc is not + dnl affected, since it uses different source code for strcasestr + dnl than glibc. + dnl Assume that it works on all other platforms, even if it is not + dnl linear. + AC_EGREP_CPP([Lucky user], + [ +#ifdef __GNU_LIBRARY__ + #include <features.h> + #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \ + || defined __UCLIBC__ + Lucky user + #endif +#elif defined __CYGWIN__ + #include <cygwin/version.h> + #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7) + Lucky user + #endif +#else + Lucky user +#endif + ], + [gl_cv_func_strcasestr_works_always="guessing yes"], + [gl_cv_func_strcasestr_works_always="$gl_cross_guess_normal"]) + ]) + ]) + case "$gl_cv_func_strcasestr_works_always" in + *yes) ;; + *) + REPLACE_STRCASESTR=1 + ;; + esac + fi + fi +]) # gl_FUNC_STRCASESTR_SIMPLE + +dnl Additionally, check that strcasestr is efficient. +AC_DEFUN([gl_FUNC_STRCASESTR], +[ + AC_REQUIRE([gl_FUNC_STRCASESTR_SIMPLE]) + if test $HAVE_STRCASESTR = 1 && test $REPLACE_STRCASESTR = 0; then + AC_CACHE_CHECK([whether strcasestr works in linear time], + [gl_cv_func_strcasestr_linear], + [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ +#include <signal.h> /* for signal */ +#include <string.h> /* for strcasestr */ +#include <stdlib.h> /* for malloc */ +#include <unistd.h> /* for alarm */ +static void quit (int sig) { _exit (sig + 128); } +]], [[ + int result = 0; + size_t m = 1000000; + char *haystack = (char *) malloc (2 * m + 2); + char *needle = (char *) malloc (m + 2); + /* Failure to compile this test due to missing alarm is okay, + since all such platforms (mingw) also lack strcasestr. */ + signal (SIGALRM, quit); + alarm (5); + /* Check for quadratic performance. */ + if (haystack && needle) + { + memset (haystack, 'A', 2 * m); + haystack[2 * m] = 'B'; + haystack[2 * m + 1] = 0; + memset (needle, 'A', m); + needle[m] = 'B'; + needle[m + 1] = 0; + if (!strcasestr (haystack, needle)) + result |= 1; + } + /* Free allocated memory, in case some sanitizer is watching. */ + free (haystack); + free (needle); + return result; + ]])], + [gl_cv_func_strcasestr_linear=yes], [gl_cv_func_strcasestr_linear=no], + [dnl Only glibc > 2.12 and cygwin > 1.7.7 are known to have a + dnl strcasestr that works in linear time. + AC_EGREP_CPP([Lucky user], + [ +#include <features.h> +#ifdef __GNU_LIBRARY__ + #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \ + && !defined __UCLIBC__ + Lucky user + #endif +#endif +#ifdef __CYGWIN__ + #include <cygwin/version.h> + #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7) + Lucky user + #endif +#endif + ], + [gl_cv_func_strcasestr_linear="guessing yes"], + [gl_cv_func_strcasestr_linear="$gl_cross_guess_normal"]) + ]) + ]) + case "$gl_cv_func_strcasestr_linear" in + *yes) ;; + *) + REPLACE_STRCASESTR=1 + ;; + esac + fi +]) # gl_FUNC_STRCASESTR + +# Prerequisites of lib/strcasestr.c. +AC_DEFUN([gl_PREREQ_STRCASESTR], [ + : +]) |